This invention relates to damping devices of the type used to smooth the output of stepping motors and deals more particularly with such a device of low cost and adapted for use with rotary output stepping motors.
Stepping motors, being essentially digital in nature, are widely used in computer controlled systems for driving parts in situations where accurate control of displacement is needed. As an example, stepping motors are often used to drive the X and Y carriages of an X-Y plotter to accurately position a recording pen or other instrument relative to a recording surface. A disadvantage of stepping motors, however, is that because of their stepwise excitation a certain amount of oscillation of the motor armature occurs at the end of each step. The degree of this oscillation is often acceptable at most excitation frequencies, but when the excitation frequency nears and reaches the resonant frequency of the motor the oscillation may become excessive.
To solve this problem, various different vibration damping devices have been proposed in the past for use with stepping motors. One such device is shown for example in prior U.S. Pat. No. 3,656,014 wherein for a linear stepping motor an inertial mass is connected to the armature of the motor through a viscoelastic member.
The purpose of this invention is to provide a damping device using somewhat the same damping principle as that of prior U.S. Pat. No. 3,656,014, although not necessarily including any elasticity providing member, adapted for use with a rotary stepping motor and capable of being made at low cost using standard readily available components.
Other objects and advantages of the invention will be apparently from the following detailed description of the invention and from the accompanying drawings.